Schenberg L C, Lovick T A
Department of Physiology, Medical School, University of Birmingham, United Kingdom.
Am J Physiol. 1995 Dec;269(6 Pt 2):R1378-89. doi: 10.1152/ajpregu.1995.269.6.R1378.
In rats anesthetized with alfaxalone/alfadolone, electrical stimulation in the dorsal periaqueductal gray matter (PAG) evoked a cardiovascular defense reaction with increases in blood pressure, heart rate, femoral conductance, and respiratory activity but a decrease in renal conductance. These responses were attenuated significantly after microinjection of 200 nl 0.1 M DL-homocysteic acid (DLH) into nucleus raphe magnus (NRM, n = 12) or nucleus raphe obscurus (NRO, n = 22). The maximum reduction in the pressor response was similar after stimulation in NRM (-36.3%) and NRO (-37.3%). The reduction of the tachycardia, however, was greater after stimulation in NRM (-78.1%) compared with NRO (-34.6%). The maximum reduction in the PAG-evoked vasodilation of the hindlimb averaged -55.7% and -55.3% after stimulation of NRM and NRO, respectively, whereas the renal vasoconstriction was reduced by -66.4% and -79.0%. The PAG-evoked increase in respiratory amplitude was attenuated only after stimulation of NRO. It is concluded that neurons in NRM and NRO may be involved in modulating the level of excitability of neurons in the midbrain defense area and/or in its efferent pathway.
在用阿法沙龙/阿法多龙麻醉的大鼠中，对中脑导水管周围灰质（PAG）进行电刺激会引发心血管防御反应，表现为血压升高、心率加快、股动脉传导增加、呼吸活动增强，但肾动脉传导降低。向中缝大核（NRM，n = 12）或中缝隐核（NRO，n = 22）微量注射200 nl 0.1 M DL-高半胱氨酸（DLH）后，这些反应显著减弱。刺激NRM（-36.3%）和NRO（-37.3%）后，升压反应的最大降低幅度相似。然而，刺激NRM（-78.1%）后的心动过速降低幅度大于刺激NRO（-34.6%）后的降低幅度。刺激NRM和NRO后，PAG诱发的后肢血管舒张的最大降低幅度分别平均为-55.7%和-55.3%，而肾血管收缩分别降低了-66.4%和-79.0%。PAG诱发的呼吸幅度增加仅在刺激NRO后减弱。结论是，NRM和NRO中的神经元可能参与调节中脑防御区神经元及其传出通路的兴奋性水平。
